Mixed salts of magnesium of 2-methoxy-3,6-dichlorobenzoic acid and a carboxylic acid

ABSTRACT

This invention discloses mixed salts of magnesium having the empirical formula   WHEREIN R is an organic acid radical of 7 to 20 carbon atoms; and n has an average value of from 0.5 to 1.5. The compounds of the above description are useful as herbicides.

United States Patent 1 1! 3,910,974

Hokama 1 Oct. 7, 1975 l MIXED SALTS 0F MAGNESIUM OF PrimarylixuminerPatrick P. Garvin 2-METHOXY-3.6-DICHLOROBENZOIC ACID AND ACARBOXYLIC ACID Inventor: Takeo Hokama, Chicago, lll.

Assignee: Velsicol Chemical Corporation,

Chicago, Ill,

Filed: Oct. 15, 1973 Appl. No.: 406,512

References Cited FOREIGN PATENTS OR APPLICATIONS 4/]966 Canada 71/115Amlstanl E.\'aminer-P E. Konopka Attorney, Agem, 0r Firm Roberl J.Schwarz; Dietmar H, Olesch 57 ABSTRACT This invention discloses mixedsalts of magnesium having the empirical formula OCH Cl Mo o-c R whereinR is an organic acid radical of 7 to 20 carbon atoms; and n has anaverage value of from 0.5 to L5. The compounds of the above descriptionare useful as herbicides,

7 Claims, N0 Drawings MIXED SALTS ()F MAGNESIUM OF2-METHOXY-3,(i-DICHLOROBENZOIC ACID AND A CARBOXYLIC ACID This inventionrelates to new compositions of matter and more specifically relates tonew mixed salts of magnesium having the empirical formula wherein R isan organic acid radical having from 7 to carbon atoms; and n has anaverage value of from 0.5 to L5.

The compounds of the present invention are useful as herbicides andpossess the unexpected property of resisting leaching in the soil.

Weeds often grow near the soil surface whereas many beneficial plantshave their roots deeper in the ground. Thus, to avoid injury to thebeneficial plants which may be partially sensitive to a herbicide, it isdesirable to minimize leaching or downward movement of the herbicide inthe soil. Furthermore, a basis for the preemergence action of herbicidesis often the difference in depth between the planted crop seeds and theweed seeds on the surface of the soil. Crop seeds are generally plantedone to three inches deep and are somewhat protected from chemicalsapplied to the soil surface, while weed seeds generally germinate onlyin the top one-fourth inch of the soil and are thus subject to a muchhgiher concentration of the chemical. To maintain this difference inconcentration of the chemical, it is desirable to have a herbicide whichis resistant to leaching in the soil. The compounds of the presentinvention resist leaching to a high degree.

The compounds of the present invention can be prepared by reacting amagnesium salt of an organic acid having from 7 to 20 carbon atoms withan appropriate amount of 2-methoxy-3,b-dichlorobenzoic acid according tothe following equation:

wherein R and n are as heretofore described. This reaction can beeffected by combining the reactants in an inert organic reaction mediumsuch as benzene, toluene, or xylene and heating the reaction mixture atreflux for a period of from about 1 to about 24 hours. After this timethe reaction mixture can be stripped to solvent under reduced pressureto yield the desired product.

The mixed magnesium salts of the present invention can also be preparedby reacting an inorganic water soluble magnesium salt such as magnesiumnitrate, magnesium sulfate, magnesium chloride and the like withappropriate amounts of an alkali metal salt of a 2-methoxy-3,o-dichlorobenzoic acid and an alkali metal salt of an organicacid having from 7 to 20 carbon atoms according to the followingexemplary equation:

Mg(C,,H OCH;,Cl CO ),,(R) M21 wherein R and n as heretofore described.This reaction can be effected by adding an aqueous solution of theinorganic magnesium salt to the appropriate stoichiometric mixture ofthe salts of the organic acids in an O OCH Cl aqueous reaction medium.The resulting mixture can be heated at temperatures of from about 60 toabout 95C for a period of up to several hours. After this time, thedesired product can be recovered by filtration and can be used as suchor can be further purified by conventional means.

The sodium salts of the organic acids can also be prepared in situ byusing a strong basic reaction medium such as an aqueous alkali metalhydroxide.

As previously indicated, the R group is an organic acid radical havingfrom 7 to 20 carbon atoms. Suitable acids which can be used in the formof their alkali metal salts such as the sodium or potassium salt toprepare the compounds of this invention and obtain the desired R groupaliphatic acids, oenanthic acid, caprylic acid,

pelargonic acid, capric acid, neodecanoic acid, undeeanoic acid, lauricacid, tridecanoic acid, myristic acid, pentadecanoic acid, palmiticacid, margaric acid and stearic acid; aromatic acids such as benzoicacid, toluic acid, ethylbenzoic acid, t-butylbenzoic acid, phthalicacid, isophthalic acid, 3-chlorobenzoic acid, 4-chlorobenzoic acid,3,4-dichlorobenzoic acid, 2,4- dichlorobenzoic acid,2,4,6-trichlorobenzoic acid, 2,4,5-trichlorobenzoic acid,2-methyl-4-chlorobenzoic acid, phenylacetic acid, 3-chlorophenylaceticacid, 4- chlorophenylacetic acid, 2,4-dichlorophenylacetic acid,3,4-dichlorophenylacetic acid, 2,4,5-trichlorophenylacetic acid,phenoxyacetic acid, 2,4-dichlorophenoxyacetic acid,3,4-dichlorophenoxyacetic acid, 2,4,S-trichlorophenoxyacetic acid andthe like.

The manner in which the compounds of the present invention can beprepared is more specifically illustrated in the following examples.

EXAMPLE 1 Preparation of a Mixed Salt of Magnesium,2-Methoxy-3,6-dichlorobenzoic Acid and Stearic Acid of the EmpiricalFonnula Mg(C.,H OCH Cl- CO in as e) product having the empirical formulagl n 2 a 2 2) m as 2 EXAMPLE 2 Preparation of a Mixed Salt of Magnesium,2-Methoxy-3,6-dichlorobenzoic Acid and Stearic Acid of the EmpiricalFormula Mg(C.,H OCH Cl CO- m :i5 2)i..s

Magnesium stearate, Mg(C ,H ,-,O (88.8 grams; 0.15 mole),2-methoxy-3,-dichlorobenzoic acid (ll grams; 0.5 mole) and benzene (300ml.) are charged into a glass reaction flask equipped with a mechanicalstirrer. thermometer and reflux condenser. The reaction mixture isheated at a temperature of about C until solution occurs. After thistime, the reaction mixture is stripped of solvent under reduced pressureto yield the desired product as a solid having the empirical formulaMg(C.,H OCH Cl C 2)u.s (C,,,H O

EXAMPLE 3 Preparation of a Mixed Salt of Magnesium.2-Methoxy-3,6-dichlorobenzoic Acid and Stearic Acid of the EmpiricalFormula Mg(C.,-H OCH;,Cl CO l8 -15 2 )0.-'')

A solution of 2-methoxy-3.6-dichlorobenzoic acid (33.l grams; 0.15 mole)in benzene (250 ml.) is placed into a glass beaker and magnesiumstearate, Mg(C H O (59.1 grams; 0.10 mole) is added thereto. The mixtureis heated on a steam bath with stirring until gellation occurs. Thegelled product is then stripped of solvent to yield a solid product.This product is further dried in a vaccum oven at l00C under aspiratorpressure. A portion of the resulting product grams) is then charged withxylene (50 grams) into a flask equipped with a reflux condenser. Themixture is then heated at reflux to yield a solution of the desiredproduct of the empirical formula g( CHHZOCHHCIZCOZ 1.5 in as a )irs-EXAMPLE 4 Preparation of a Mixed Salt of Magnesium,2-Methoxy-3,fi-dichlorobenzoic Acid and Stearic Acid of the EmpiricalFormula Mg(C H OCH Cl CO (C 2-Methoxy-3.o-dichlorobenzoic acid (11.05grams; 0.05 mole) and stearic acid (l4.22 grams; 0.05 mole) are added toa solution of sodium hydroxide (4 grams;

0. l0 mole) in water (50 ml. The mixture is heated to melt the stearicacid thereby forming a heterogeneous solution. The solution is thenadded to a solution of magnesium chloride (4.76 grams; 0.05 mole) inwater (100 ml.) with vigorous stirring. Stirring is continued for aperiod of about 60 minutes to yield a solid product. This product isrecovered by filtration, is washed with water and is dried under vacuumat l00C. Five grams of this product is then dissolved in xylene to yielda solution of the desired product of the empirical formula Mg(C HOCH;;Cl- CO (C H O EXAMPLE 5 Preparation of a Mixed Salt of Magnesium.2-Methoxy-3,fi-dichlorobenzoic Acid and Benzoic Acid of the EmpiricalFormula Mg(C H OCH,,Cl CO fi 5 2) Z-Methoxy-3,6-dichlorobenzoic acid(33.15 grams; 87% assay 0.15 mole), benzoic acid (18.3 grams; 0. l5mole), sodium hydroxide [2.0 grams; 0.3 mole) and water (300 ml.) arecharged into a glass reaction vessel equipped with a mechanical stirrerand reflux condenser. The mixture is heated to 90C and a solution ofmagnesium chloride [4.28 grams; 0. l5 mole) in water (100 ml.) is addedwith stirring. The mixture is reheated to 90C and is then allowed tocool to room temperature. The cooled mixture is then filtered to recoverthe desired product as a pwodered solid having the empirical formula Mg(C -H OCH Cl CO f s s zl- EXAMPLE 6 Preparation of a Mixed Salt ofMagnesium. 2'Methoxy-3.6-dichlorobenzoic Acid and Octanoic Acid of theEmpirical Formula Mg(C.-,H OCH;,CI CO 8 l5 'Z)2-Methoxy-3.o-dichlorobenzoic acid (33.15 grams;

87% assay; 0.15 mole). octanoic acid (21.6 grams; 0. [5 mole). sodiumhydroxide (l2.0 grams; 0.3 mole) and water are charged into a reactionvessel equipped with thermometer and mechanical stirrer. The mixture isheated to a temperature of about 90C and a solution of magnesiumchloride (l4.28 grams; 0.15 mole) in water (100 ml.) is added thereto.The mixture is reheated to a temperature of about C and is then allowedto cool to room temperature. The solid formed is recovered byfiltration; washed with water and dried. The dried product is thenrefluxed in xylene to yield a solution of the desired product having theempirical formula Mg(C,;H OCH Cl CO (C H O EXAMPLE 7 Preparation of aMixed Salt of Magnesium, Z-Methoxy-3,6-dichlorobenzoic Acid and ToluicAcid of the Empirical Formula Mg(C ,-H OCH;,Cl CO (CGH-ICH3CO2)2-Methoxy-3,6-dichlorobenzoic acid (33.15 grams; assay; 0.15 mole),toluic acid (0. l 5 mole). sodium hydroxide l2.0 grams; 0.3 mole) andwater (250 ml.) are charged into a glass reaction vessel equipped with amechanical stirrer and thermometer. The mixture is heated to atemperature of about 85C and a solution of magnesium chloride (0.l5mole) in water [00 ml.) is added thereto. The mixture is then heated atabout C for a period of about 60 minutes with continued stirring. Afterthis time the reaction mixture is cooled to room temperature and isfiltered to recover solid product. This solid is then washed with waterand is dried to yield the desired product of the empirical formulil(CgHgOCHgClgCO-z) (C6H4CH3CO2).

EXAMPLE 8 Preparation of a Mixed Salt of Magnesium,2-Methoxy-3,6-dichlorobenzoic Acid and Oenanthic Acid of the EmpiricalFormula Mg(C H OCH Cl C0 ti l3 2) 2-Methoxy-3,6-dichlorobenzoic acid(0.15 mole), oenanthic acid (0.l5 mole), sodium hydroxide (l2.0 grams)and water (250 ml.) are charged into a glass reaction vessel equippedwith 'a mechanical stirrer and thermometer. The mixture is heated to atemperature of about 90C and a solution of magnesium chloride (0. 15mole) in water ml.) is added thereto. The mixture is then heated to atemperature of about 90C for a period of about 45 minutes with continuedstirring. After this time, the reaction mixture is cooled to roomtemperature and is filtered to recover solid product. This solid is thenwashed with water and is dried to yield the desired product of theempirical formula g( n z a z -zl ti m Z EXAMPLE 9 Preparation of a MixedSalt of Magnesium, 2-Methoxy-3.6-dichlorobenzoic Acid and Caprylic Acidof the Empirical Formula Mg(C H OCH Cl CO v us z)2-Methoxy-3,6-dichlorobenzoic acid (0.15 mole), caprylic acid (0.l5mole), sodium hydroxide (l2.0 grams) and water (250 ml.) are chargedinto a glass reaction vessel equipped with a mechanical stirrer andthermometer. The mixture is heated to a temperature of about 85C and asolution of magnesium chloride (0.15 mole) in water l00 ml.) is addedthereto. The

mixture is then heated at about 85C for a period of about 60 minuteswith continued stirring. After this time the reaction mixture is cooledto room temperature and is filtered to recover solid product. This solidPreparation of a Mixed Salt of Magnesium, 2-Methoxy-3,o-dichlorobenzoicAcid and t-Butylbenzoic Acid of the Empirical Formula s z a z zl B -i -iS 'AZ) 2-Methoxy-3.o-dichlorobenzoic acid (0.1 1 mole), t-butylbenzoicacid (0.1 1 mole), sodium hydroxide (8.8 grams) and water (250 ml.) arecharged into a glass reaction vessel equipped with a mechanical stirrerand thermometer. The mixture is heated to a temperature of about 80C anda solution of magnesium chloride (0. l l mole) in water (100 ml.) isadded thereto. The mixture is then heated at about 80C for a period ofabout 90 minutes with continued stirring. After this time, the reactionmixture is cooled to room temperature and is filtered to recover solidproduct. This solid is then washed with water and is dried to yield thedesired product of the empirical formula Mg(C,,H ,OCH Cl C (C H C H COEXAMPLE 1 1 Preparation of a Mixed Salt of Magnesium,2-Methoxy-3,o-dichlorobenzoic Acid and 2.4-Dichlorophenoxyacetic Acid ofthe Empirical Formula Mg(C,,H OCH,-;Cl CO- (C H Cl OCH CO2-Methoxy-3.fi-dichlorobenzoic acid (33. l grams; 8571 assay; 0. l 5mole), 2,4-dichlorophenoxyacetic acid (33 grams; 0. l5 mole), sodiumhydroxide (12 grams) and water (250 ml.) are charged into a reactionvessel equipped with thermometer and mechanical stirrer. The mixture isheated to a temperature of about 90C and a solution of magnesiumchloride (14.28 grams; 0.15 mole) in water (l00 ml.) is added thereto.The mixture is reheated to a temperature of about 80C and is thenallowed to cool to room temperature. The solid formed is recovered byfiltration, is washed with water and is dried to yield the desiredproduct of the empirical formula Mg(C,;H OCH -;Cl CO (C H CI OCH- 2CO2)-EXAMPLE 12 Preparation of a Mixed Salt of Magnesium,2-Methoxy3,o-dichlorobenzoic Acid and 2,4-Dichlorobenzoic Acid of theEmpirical Formula gl u z s z -zl n a z 2) 2-Methoxy-3,6-dichlorobenzoicacid (33.15 grams; 85% assay; 0.15 mole). 2,4-dichlorobenzoic acid (28.7grams; 0.15 mole), sodium hydroxide (12 grams; 0.3 mole) and water (250ml.) are charged into a glass reaction vessel equipped with athermometer and mechanical stirrer. The mixture is heated to atemperature of about 90C and a solution of magnesium chloride [4.28grams; 0.15 mole) in water (100 ml.) is added thereto. The mixture isreheated to a temperature of about 80C and is then allowed to cool toroom temperature. The solid formed is recovered by filtration. is\ulsht'd with water and is dried to yield the dc lred product of theempirical formula Mg(C,,H OCH Cl- QCOZ) ti 3l 2 2)- For practical use asherbicides the compounds of this invention are generally incorporatedinto herbicidal compositions which comprise an inert carrier and aherbicidally toxic amount of such a compound. Such herbicidalcompositions, which can also be called formulations, enable the activecompound to be applied conveniently to the site of the weed infestationin any desired quantity. These compositions can be solids such as dusts,granules, or wettable powders; or they can be liquids such as solutions,aerosols, or emulsifiable concentrates.

For example, dusts can be prepared by grinding and bledning the activecompound with a solid inert carrier such as the talcs, clays, silicas,pyrophyllite, and the like. Granular formulations can be prepared byimpregnating the compound, usually dissolved in a suitable solvent, ontoand into granulated carriers such as the attapulgites or thevenniculites, usually of a particle size range of from about 0.3 to L5mm. Wettable pow ders, which can be dispersed in water or oil to anydesired concentration of the active compound, can be prepared byincorporating wetting agents into concentrated dust compositions.

In some cases the active compounds are sufficiently soluble in commonorganic solvents such as kerosene or xylene so that they can be useddirectly as solutions in these solvents. Frequently, solutions ofherbicides can be dispersed under super-atmospheric pressure asaerosols. However, preferred liquid herbicidal compositions areemulsifiable concentrates. which comprise an active compound accordingto this invention and as the inert carrier, a solvent and an emulsifier.Such emulsifiable concentrates can be extended with water and or oil toany desired concentration of active compound for application as spraysto the site of the weed infestation. The emulsifiers most commonly usedin these concentrates are nonionic or mixtures of nonionic with anionicsurface-active agents. With the use of some emulsifier systems aninverted emulsion (water in oil) can be prepared for direct applicationto weed infestations.

A typical herbicidal composition according to this invention isillustrated by the following example, in which the quantities are inparts by weight.

EXAMPLE 13 Preparation of a Dust Product of Example 1 lO Powdered TalcThe above ingredients are mixed in a mechanical grinder-blender and areground until a homogeneous, free-flowing dust of the desired particlesize is obtained. This dust is suitable for direct application to thesite of the weed infestation.

The compounds of this invention can be applied as herbicides in anymanner recognized by the art. One method for the control of weedscomprises contacting the locus of said weeds with a herbicidalcomposition comprising an inert carrier and as an essential activeingredient, in a quantity which is herbicidally toxic to said weeds, acompound of the present invention. The concentration of the newcompounds of this invention in the herbicidal compositions will varygreatly with the type of formulation and the purpose for which it isdesigned. but generally the herbicidal compositions will comprise fromabout 0.05 to about 95 percent by weight of the active compounds of thisinvention. in a preferred embodiment of this invention, the herbicidalcompositions will comprise from about 5 to about 75 percent by weight ofthe active compound. The compositions can also comprise such additionalsubstances as other pesticides, such as insecticides. nematocides.fungicides, and the like; stabilizers. spreaders, deactivators,adhesives, stickers, fertilizers, activators, synergists, and the like.

The compound of the present invention are also useful when combined withother herbicides and/or defoliants, dessicants, growth inhibitors, andthe like in the herbicidal compositions heretofore described. Theseother materials can comprise from about 5 to about 95 percent of theactive ingredients in the herbicidal compositions. Use of combinationsof these other herbicides and/or defoliants, dessicants, etc. with thecompounds of the present invention provide herbicidal compositions whichare more effective in controlling weeds and often provide resultsunattainable with separate compositions of the individual herbicides.The other herbicides. defoliants, dessicants and plant growthinhibitors, with which the compounds of this invention can be used inthe herbicidal compositions to control weeds, can include chlorophenoxyherbicides such as 2,4-D, 2,4,5-T, MCPA, MCPB, 4(2,4-DB), 2,4- DEB,4-CPB, 4-CPA, 4-CPP. 2,4,5-TB, 2,4,5-TES, 3,4- DA, silvex and the like;carbamate herbicides such as IPC, CIPC, swep, barban, BCPC, CEPC, CPPC,and the like; thiocarbamate and dithiocarbamate herbicides such as CDEC,metham sodium, EPTC, diallate, PEBC, perbulate, vernolatc and the like;substituted urea herbicides such as norea, siduron. dichloral urea,chloroxuron, cycluron, fenuron. monuron, monuron TCA, diuron, linuron.monolinuron, neburon, buturon, trimetu' ron and the like; symmetricaltriazine herbicides such as simazine, chlorazine, atraone, desmetryne,norazine. ipazine, prometryn, atazine, trietazine, simetone. prometone.propazine. ametryne, and the like; chloroacetamide herbicides such asalpha-chloro-N, N- dimethylacetamide, CDEA, CDAA, alpha-chloro-N-isopropylacetamide, 2-chloro-N-isopropylacetanilide. 4-( chloroacetyl)morpholine, l- (chloroacetyl)piperidine, and the like; chlorinatedaliphatic acid herbicides such as TCA, dalapon, 2,3- dichloropropionicacid, 2,2,3-TPA and the like; chlorinated benzoic acid and phenylaceticacid herbicides such as 2,3,6-TBA. 2,3,5,6-TBA, tricamba, amiben, fenac,PBA, 2-methoxy-3,6-dichlorophenylacetic acid,3-methoxy-2,o-dichlorophenylacetic acid, Z-methoxy-3,5,o-trichlorophenylacetic acid, 2,4-dichloro-3- nitrobenzoic acid andthe like; and such compounds as aminotriazole, maleic hydrazide, phenylmercuric acetate, endothal, biuret. technical chlordane, dirnethyl2,3,5,o-tetrachloroterephthalate. diquat, erbon, DNC, DNBP. dichlobenil,DPA, diphenamid, dipropalin. trifluralin, solan, dicryl, merphos, DMPA.DSMA, MSMA. potassium azide, acrolein, benefin, bensulide, AMS,bromacil, 2(3,4-dichlorophenyl)-4-methyll,2,4-oxadiazolidine-3,S-dione,bromoxynil, cacodylic acid, CMA, CPMF. cypromid, DCB. DCPA, dichlone.diphenatril. DMTT. DNAP, EBEP, EXD, HCA, ioxynil. IPX, isocil, potassiumcyanate, MAA. MAMA, MCPES. MCPP, MH. molinatc, NPA, OCH paraquat, PCP,picloram, DPA. PCA, pyrichlor. sesone. terbacil, terbutol, TCBA.brominil. CP-5Ul44, H- l76-l. H-732.

M2901, planavin. sodium tetraborate. calcium cyanamid, DEF. ethylxanthogen disulfide, sindone. sindone B. propanil and the like.

Such herbicides can also be used in the methods and compositions of thisinvention in the form of their salts. esters. amides, and otherderivatives whenever applicable to the particular parent compounds.

Weeds are undesirable plants growing where they are not wanted, havingno economic value. and interfering with the production of cultivatedcrops, with the growing of ornamental plants, or with the welfare oflivestock. Many types of weeds are known, including annuals such aspigweed, lambsquarters, foxtail, crabgrass, wild mustard, fieldpennycress, ryegrass, goose-grass, chickweed, wild oats, velvet leaf,purselane, barnyard grass. smartweed, knotweed, cocklebur, wildbuckwheat, kochia, medic. corn cockle, ragweed. sowthistle, coffee-weed,croton. cuphea. dodder. fumitory, groundsel, hemp nettle, knowel,spurge, spurry. emex, jungle rice, pondweed. dog fennel, carpetweed,morning glory, bedstraw, ducksalad and naiad; biennials such as wildcarrot, matricaria, wild barley, campion, chamomile, burdock, mullein,round-leaved mallow. bull thistle, hounds-tongue, moth mullein, andpurple star thistle; or perennials such as white cockle, perennialrye-grass, quackgrass, Johnson grass, Canada thistle, hedge bindweed.Bermuda grass, sheep sorrel, curley dock, nutgrass, field chickweed,dandelion, campanula, field bindweed, Russian knapweed, mesquite,toadflax. yarrow, aster, gromwell, horsetail, ironweed, sesbania,bulrush, cattail and winter-cress.

Similarly, such weeds can be classified as broadleaf or grassy weeds. Itis economically desirable to control the growth of such weeds withoutdamaging beneficial plants or livestock.

The new compounds of this invention are particularly valuable for weedcontrol because they are toxic to many species and groups of weeds whilethey are relatively non-toxic to many beneficial plants. The exactamount of compound required will depend on a variety of factors,including the hardiness of the particular weed species, weather, type ofsoil, method of application, the kind of beneficial plants in the samearea, and the like. Thus, while the application of up to only about oneor two ounces of active compound per acre may be sufficient for goodcontrol of a light infestation of weeds growing under adverseconditions, the application of ten pounds or more of an active compoundper acre may be required for good control of a dense infestation ofhardy perennial weeds growing under favorable conditions.

The herbicidal toxicity of the new compounds of this invention can beillustrated by many of the established testing techniques known to theart, such as preand post-emergence testing.

The herbicidal activity of the compounds of this invention can bedemonstrated by experiments carried out for the pre-emergence control ofa variety of weeds. in these experiments small plastic greenhouse potsfilled with dry soil are seeded with the various weed seeds. Twenty-fourhours or less after seeding the pots are sprayed with water until thesoil is wet and the test compounds formulated as aqueous emulsions ofacetone solutions containing emulsifiers are sprayed at the desiredconcentrations on the surface of the soil.

After spraying, the soil containers are placed in the greehouse andprovided with supplementary heat as required and daily or more frequentwatering. The plants are maintained under these conditions for a periodof from l to 2] days. at which time the condition of the plants and thedegree of injury to the plants is rated on a scale of from U to l(). asfollows: i) no injury. 1.2 =slight injury. 3.4 moderate injury, 5.6moderately severe injury. 7.8.9 =severe injury and l()=death. Theeffectiveness of the compounds of this invention can be demonstrated bythe foregoing procedure.

The herbicidal activity of the compounds of this invention can also bedemonstrated by experiments carried out for the post-emergence controlof a variety of The acidified solution was extracted with chloroform andanalyzed by quantitative infra-red analysis as 2-methoxy-3.o-dichlorobenzoic acid. The stoichiomctric conversion andsubsequent analysis for the test compound in the water eluant indicatedthe amount of test compound which had passed through the soil column andis a measure of the degree of leaching of the test compound in soil. Forcomparative purposes, the identical leaching experiment was carried outusing the dimethylamine salt of Z-methoxy-3.6dichlorobenzoic acid. Theresult of these experiments is shown in the following table.

TABLE I Test Compounds Physical State on Application Amount of TestCompound Applied to the Soil Expressed as Dicamha Product of Example 1Dimcthylamine Salt of Z- Mcthox \3.fidichlorobcnloic Acid Xy lcneSolution Aqueous Solution 0.00296 grams (HEB ll) grams l()3.(1

Dicamlm 1 nictho\y-3.h'dichlorobcn/oic acid weeds. In these experimentsthe compounds to be tested are formulated as aqueous emulsions andsprayed at the indicated dosage on the foliage of the various weedspecies that have attained a prescribed size. After spraying, the plantsare placed in a greenhouse and watered daily or more frequently. Wateris not applied to the foliage of the treated plants. The severity of theinjury is determined 10 to l5 days after treatment and is rated on thescale of from O to 10 heretofore described.

The resistance to leaching of the compounds of the present invention wasdemonstrated in experiments wherein the migration of the compounds ofthis invention through soil was measured. In these experiments a plasticcolumn was packed with soil which had previously been dried and passedthrough a mesh screen. The column was packed to a soil depth of 3inches. The test compounds were then applied to the soil surface in theform of a solid powder or xylene solution and water (284 ml.) equivalentto 6 inches of rainfall was then poured on top of the soil column in asingle addition. The column was allowed to stand for a period of 24hours during which time the water slowly eluted from the bottom of thecolumn was collected. The water eluant was then analyzed for the amountof test compound present. The aqueous solution was concentrated andhydrolyzed with 50 percent aqueous hydrochloric acid.

I claim: 1. A mixed salt of magnesium having the empirical formula:

OCH Cl wherein R is an organic monocarboxylic acid radical of from 7 to20 carbon atoms and n has an average value of from 0.5 to L5.

2. A salt of claim 1 wherein n is l.

3. A salt of claim 1 wherein R is a stearic acid radical.

4. A salt of claim I wherein R is a benzoic acid radical.

5. A salt of claim I wherein R is a caprylic acid radica].

6. A salt of claim wherein R is a toluic acid radical.

7. A salt of claim 1 wherein R is t-butylbenzoic acid radical.

1. A MIXED SALT OF MAGNESIUM HAVING THE EMPERICAL FORMULA:
 2. A salt ofclaim 1 wherein n is
 1. 3. A salt of claim 1 wherein R is a stearic acidradical.
 4. A salt of claim 1 wherein R is a benzoic acid radical.
 5. Asalt of claim 1 wherein R is a caprylic acid radical.
 6. A salt of claim1 wherein R is a toluic acid radical.
 7. A salt of claim 1 wherein R ist-butylbenzoic acid radical.